These studies are aimed at identifying an effect of the peri- and post-natal rise of plasma androgens on the metabolic and mechanical properties of rat aortic elastin and collagen. The basic question under investigation is whether an androgen imprint at this early period of development initiates changes leading to the ultimate lesion of the obstructive atheroma. If an androgen imprint is found, then pharmacologic means to modify this imprint will be tested. Current data show higher concentrations of elastin and collagen in the aorta of the neonate male than in that of the neonate female. And sex differences are seen in the chemical properties of the elastin as well as in the profile of the borohydride-reducible collagen cross-links. Goals for the forthcoming year are to contrast the metabolic properties of aortic elastin and collagen during the early developmental period in the male and female rat and to examine for sex differences in the stability of intermolecular collagen cross-links.